scripts: build-chromium: Set channel to stable

* Removes the unknown from chrome://version

Change-Id: Ie8b6e04977421e841a357480a92377f4a790f85c
diff --git a/build-chromium/build-chromium.sh b/build-chromium/build-chromium.sh
index b947f5d..4356c6e 100755
--- a/build-chromium/build-chromium.sh
+++ b/build-chromium/build-chromium.sh
@@ -106,6 +106,7 @@
 
 # Build args
 args='target_os="android"'
+args+=' android_channel="stable"'
 args+=' is_debug=false'
 args+=' is_official_build=true'
 args+=' is_chrome_branded=false'